Protective role of sodium para-amino salicylic acid against manganese-induced hippocampal neurons damage

Manganese (Mn) is an essential trace element of human. However, excessive Mn can cause manganism. Mn selectively accumulated in Mn-exposed workers’ hippocampus which is crucial for higher brain functions such as learning, memory, and motivation during our postnatal life. Studies suggested sodium para-aminosalicylic acid (PAS) appeared to be therapeutic for manganism. We aimed to explore whether PAS could block Mn-induced neuronal injury in hippocampus in vitro. Hippocampal neurons were exposed to 50 μM manganese chloride (MnCl₂) for 24 h, following by 50, 500, or 5000 μM PAS treatment for 24 h. Cell viability, apoptosis rate, mean fluorescence intensity of mitochondrial and DNA damage were respectively performed. MnCl₂ significantly decreased neurons’ viability and fluorescence intensity of comet head of DNA, while increasing the apoptosis rate, mean fluorescence intensity of mitochondrial, percentage of tail DNA, and Olive tail moment of DNA. PAS reduced the percentage of tail DNA and Olive tail moment of Mn-exposed neurons. These data suggested that Mn caused hippocampal neurons’ injury, and 50–5000 μM PAS could inhibit Mn-induced DNA damage.     

A Model of TMS-induced I-waves in Motor Cortex

BackgroundTranscranial magnetic stimulation (TMS) allows to manipulate neural activity non-invasively, and much research is trying to exploit this ability in clinical and basic research settings. In a standard TMS paradigm, single-pulse stimulation over motor cortex produces repetitive responses in descending motor pathways called I-waves. However, the details of how TMS induces neural activity patterns in cortical circuits to produce these responses remain poorly understood. According to a traditional view, I-waves are due to repetitive synaptic inputs to pyramidal neurons in layer 5 (L5) of motor cortex, but the potential origin of such repetitive inputs is unclear.Objective/hypothesisHere we aim to test the plausibility of an alternative mechanism behind D- and I-wave generation through computational modeling. This mechanism relies on the broad distribution of conduction delays of synaptic inputs arriving at different parts of L5 cells' dendritic trees and their spike generation mechanism.MethodsOur model consists of a detailed L5 pyramidal cell and a population of layer 2 and 3 (L2/3) neurons projecting onto it with synapses exhibiting short-term depression. I-waves are simulated as superpositions of spike trains from a large population of L5 cells.ResultsOur model successfully reproduces all basic characteristics of I-waves observed in epidural responses during in vivo recordings of conscious humans. In addition, it shows how the complex morphology of L5 neurons might play an important role in the generation of I-waves. In the model, later I-waves are formed due to inputs to distal synapses, while earlier ones are driven by synapses closer to the soma. Finally, the model offers an explanation for the inhibition and facilitation effects in paired-pulse stimulation protocols.ConclusionsIn contrast to previous models, which required either neural oscillators or chains of inhibitory interneurons acting upon L5 cells, our model is fully feed-forward without lateral connections or loops. It parsimoniously explains findings from a range of experiments and should be considered as a viable alternative explanation of the generating mechanism of I-waves.     

星形胶质细胞在脑缺血损伤中的作用及其机制

背景 脑血管疾病严重危害人类健康,其中脑卒中是我国60岁以上人群致死第二大病因,同时因其高致残性愈发受到关注。先前脑保护研究主要针对神经元受损机制,而作为中枢神经系统中数量最多的星形胶质细胞,因其在构建中枢神经系统结构、辅助细胞间信号转导、调节神经元可塑性等过程中的重要作用,成为近年来脑保护治疗研究热点。目的 探究星形胶质细胞在脑缺血性损伤中的作用。内容 综述星形胶质细胞生理功能,星形胶质细胞在脑缺血性损伤中细胞形态和功能变化,星形胶质细胞神经保护作用。 趋向 星形胶质细胞有望成为脑缺血性损伤治疗的新靶点。     

The Protective Effects of IGF-1 on Different Subpopulations of DRG Neurons with Neurotoxicity Induced by gp120 and Dideoxycytidine In Vitro

Peripheral neuropathy induced by human immunodeficiency virus (HIV) infection and antiretroviral therapy is not only difficult to distinguish in clinical practice, but also difficult to relieve the pain symptoms by analgesics because of the severity of the disease at the later stage. Hence, to explore the mechanisms of HIV-related neuropathy and find new therapeutic options are particularly important for relieving neuropathic pain symptoms of the patients. In the present study, primary cultured embryonic rat dorsal root ganglion (DRG) neurons were used to determine the neurotoxic effects of HIV-gp120 protein and/or antiretroviral drug dideoxycytidine (ddC) and the therapeutic actions of insulin-like growth factor-1 (IGF-1) on gp120- or ddC-induced neurotoxicity. DRG neurons were exposed to gp120 (500 pmol/L), ddC (50 μmol/L), gp120 (500 pmol/L) plus ddC (50 μmol/L), gp120 (500 pmol/L) plus IGF-1 (20 nmol/L), ddC (50 μmol/L) plus IGF-1 (20 nmol/L), gp120 (500 pmol/L) plus ddC (50 μmol/L) plus IGF-1 (20 nmol/L), respectively, for 72 hours. The results showed that gp120 and/or ddC caused neurotoxicity of primary cultured DRG neurons. Interestingly, the severity of neurotoxicity induced by gp120 and ddC was different in different subpopulation of DRG neurons. gp120 mainly affected large diameter DRG neurons (>25 μm), whereas ddC mainly affected small diameter DRG neurons (≤25 μm). IGF-1 could reverse the neurotoxicity induced by gp120 and/or ddC on small, but not large, DRG neurons. These data provide new insights in elucidating the pathogenesis of HIV infection- or antiretroviral therapy-related peripheral neuropathy and facilitating the development of novel treatment strategies.     

海马去神经支配损伤后放射状胶质细胞表达RUNX1T1的变化及向神经元分化的影响

目的 观察海马去神经支配损伤后,海马放射状胶质细胞表达RUNX相关转录因子1转位1（RUNX1T1）和向神经元分化的情况。方法 取6只大鼠,采用物理切割大鼠穹隆海马伞术制备海马去神经支配损伤模型,并制备海马提取液,海马放射状胶质细胞体外培养,培养液中加入海马提取液。实验分为去神经支配组、正常组和空白对照组,共6块24孔板,每组各48孔。采用Real-time PCR、Western blotting及免疫荧光技术检测各组放射状胶质细胞表达RUNX1T1 mRNA和蛋白的变化,以及分化成微管相关蛋白 2（MAP-2）阳性神经元比例。结果 体外培养的海马放射状胶质细胞具有细而长的突起,且表达RUNX1T1,去神经支配组中RUNX1T1阳性细胞的荧光强度高于正常组和空白对照组约1.8倍,细胞突起也较后两组长。去神经支配组RUNX1T1 mRNA和蛋白表的表达量各上调2.9倍和2.4倍,且39.33%细胞表达MAP-2,与正常组和空白对照组相比,阳性细胞数比例明显增高。结论 海马去神经支配损伤后海马放射状胶质细胞上调表达RUNX1T1,并可更多地向神经元分化。     

骨形态发生蛋白/维甲酸诱导的神经特异性蛋白3在丙戊酸钠诱导神经干细胞向神经元分化过程中的作用

目的 探讨骨形态发生蛋白/维甲酸诱导的神经特异性蛋白3（Brinp3）在丙戊酸钠（VPA）诱导神经干细胞向神经元分化过程中的作用。方法 体外培养大鼠海马神经干细胞,运用Real-time PCR和Western blotting技术在VPA诱导神经干细胞分化后24 h和48 h检测Brinp3的表达;Real-time PCR检测Brinp3在成年大鼠各组织中以及在神经干细胞、星形胶质细胞和神经元中的表达水平;在神经干细胞中转染Brinp3小干扰RNA（siRNA）并诱导分化24 h后,运用Real-time PCR、Western blotting和免疫荧光技术检测Brinp3和神经元标志分子的表达。以上实验均包含5次生物学重复。结果 与对照组相比,VPA处理组中Brinp3的mRNA和蛋白水平在24 h和48 h均显著上调（P<0.05）;Brinp3在脑组织中呈优势表达;Brinp3在星形胶质细胞中表达较低,而在神经元中表达较高（P<0.001）;在神经干细胞中转染Brinp3 siRNA,诱导分化24 h后,Brinp3的表达被显著抑制（P<0.001）,神经元标志分子的表达均显著下调（P<0.01）,第4天分化成的神经元比例减少（P<0.001）。结论 Brinp3表达的上调可能介导了VPA促神经干细胞向神经元分化的功能。     

Spastin促进海马神经元树突野的形成

目的　探讨微管切割蛋白Spastin对海马神经元树突野形成的作用。 方法　把目的基因转染入原代海马神经元,用免疫荧光显示树突α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体,全细胞膜片钳检测微小兴奋性突触后电流（mEPSCs）。 结果　过表达Spastin促进树突生长以及分支形成,敲减Spastin抑制树突的生长和新的分支形成,与对照细胞差异有统计学意义（P<0.05）;Sholl分析结果显示Spastin提高树突野的复杂性（P<0.05）;免疫荧光结果显示,过表达Spastin促进AMPA受体GluA2亚基在树突的表达,与对照组差异有统计学意义（P<0.05）;而敲减Spastin则抑制树突GluA2的表达（P<0.05）;全细胞膜片钳检测显示,过表达Spastin神经元的mEPSCs振幅和频率均增加,敲减Spastin则使mEPSC的幅度和频率降低（P<0.05）。 结论　Spastin促进神经元树突野的形成,而且形成的树突是功能性树突。     

丹参诱导骨髓基质细胞神经元样细胞分化的microRNA-128路径

目的　研究microRNA-128在丹参制剂诱导大鼠骨髓基质细胞(bone marrow strowal cells,BMSCs)向神经元样细胞分化过程中的调控作用。  方法　培养鉴定大鼠BMSCs,应用反义寡居核苷酸转染技术（Lipofectamin 2000）转染microRNA-128 inhibitors于BMSCs;取转染和未转染的BMSCs,待细胞增殖到60%~70%融合时进行预诱导分化,预诱导24 h后,进行诱导分化;根据处理方式不同分为4组：未诱导组（A组）,丹参制剂诱导组（B组）,转染未诱导组（C组）,转染诱导组（D组）。流式细胞术鉴定BMSCs;qPCR检测microRNA-128及神经元特异性烯醇化酶（NSE）、巢蛋白（Nestin）、微管蛋白（β3-tubulin）的mRNA表达;Western blot检测NSE、Nestin和β3-tubulin的蛋白表达。  结果    BMSCs流式细胞检测CD29和CD90双阳性率达99.17%,CD11b和CD45双阴性率达99.21%;丹参制剂诱导及microRNA-128 inhibitors转染后,细胞microRNA-128表达量显著降低（P<0.05）;诱导与未诱导组,转染与未转染组比较,NSE、Nestin和β3-tubulin的mRNA和蛋白表达均显著升高（P<0.05）。  结论　丹参制剂能够抑制BMSCs的microRNA-128表达,进而影响BMSCs神经分化相关蛋白的表达,促进BMSCs向神经元样细胞分化。     

PirB抑制缺氧缺血性脑损伤新生大鼠脑组织神经再生

目的 观察缺氧缺血性脑损伤（HIBD）后新生大鼠脑组织中髓鞘抑制因子配对免疫球蛋白B（PirB）的表达变化,以及抑制PirB对缺氧缺血性神经损伤的保护作用。方法 66只新生Sprague Dawley大鼠随机分为假手术组（n=30）、HIBD组（n=30）和抗PirB抗体组（n=6）,采用结扎右侧颈总动脉和低氧（8% O2）处理3 h造模,假手术组分离右侧颈总动脉但不予结扎及缺氧处理;HIBD组在完成结扎手术及缺氧处理后,两组分别在0 h、6 h、12 h、24 h和72 h各处死6只大鼠;抗PirB抗体组在完成结扎手术及缺氧处理后即刻从脑室内注入PirB抗体,于72 h后处死。采用免疫组化、Western blot和RT-PCR方法检测HIBD后各时间点新生鼠脑组织内PirB蛋白及mRNA含量的变化,同时免疫沉淀法测定Rho激酶（ROCK）活性在HIBD 72 h后的变化以及抗PirB抗体对ROCK活性的影响。结果 PirB mRNA和蛋白均在HIBD 72 h后的新生鼠脑组织中表达升高,与HIBD后0 h比较差异均有统计学意义（均P<0.05）。HIBD后 72 h,新生鼠脑组织中ROCK蛋白活性高于假手术组和抗PirB抗体组（均P<0.05）。结论 抑制PirB可能是促进HIBD后神经再生的一个新治疗方法,而该抑制作用可能是通过Rho-ROCK信号通路产生的。     

miR-124a和miR-449a对非小细胞肺癌的诊断价值

目的 探讨微小RNA-124a(miR-124a)和微小RNA-449a(miR-449a)对非小细胞肺癌(NSCLC)的诊断价值.方法 选取行手术切除肿瘤的NSCLC患者90例(NSCLC组),出院随访36个月,根据术后复发情况分为复发组(56例)和未复发组(34例).另选取肺部良性结节患者60例(良性结节组)、健康...